MVVR and HRRV: the third agreement in the Retrofit Solution

The third agreement from PfH and Fusion21 in the Retrofit Solution covers Mechanical Ventilation with Heat Recovery (MVHR) and single room Heat Recovery Room Ventilation (HRRV) units.

As with all the Retrofit agreements, these products are intended to be procured and installed as part of a low carbon refurbishment package for existing housing stock. The overall package of measures to be installed will depend on a range of factors and the ‘whole-house’ performance standards being aimed for. The refurbishment package could be delivered all in one go or as part of an incremental improvement.  In case of the latter, it is recommended that careful consideration is given to the sequencing of measures with fabric measures prioritised over building services and renewable energy technologies. Consideration should also be given to key trigger points for implementing the upgrade measures, such as general house improvements or maintenance works, allowing both costs and ‘hassle factor’ to be reduced.

It is of paramount importance to ensure that a property is sufficiently airtight (see Insulation & Air Tightness agreement information ) otherwise the energy demand of the MVHR will exceed the energy savings in terms of heat demand reduction.

When a property has been upgraded to sufficient air tightness, a MVHR unit can be installed to ensure a fresh circulation of air around the house whilst also ensuring as much heat from the property is recovered at the same time.

An MVHR unit works by extracting warm, moist air (from the likes of kitchens and bathrooms) and the heat is then transferred to the incoming fresh air via a heat exchanger before being exhausted.

HRRVs combine supply and extract fans in a single 'through the wall' unit.

The MVHR unit, including its ductwork, must be positioned anywhere within the insulated envelope of a dwelling provided there is adequate access for its cleaning and maintenance and that any noise produced will not disturb the occupants. HRRVs, however, can be installed wherever one would position an extraction fan in wet rooms and require no ducting.

The PfH/Fusion21 Mechanical Ventilation with Heat Recovery and Heat Recovery Room Ventilation units Agreement has used extensive research and set exacting standards for suppliers to fulfil in order to ensure effectiveness, safety and compliance with Building Regulations.

The Agreement was launched in July and further information will be available to Members later in the month.